Microstructural Development and Superconducting Properties of BaO(sub2)-addedBi(sub2)Sr(sub2) CaCu(sub2)O(sub8+x)

摘要

Investigations on the effects of Ba additions in Bi-2212 superconductors arefocussed on compositional, microstructural, and magnetization studies. In previous studies, we showed that Ba02 reacts with Bi-2212 to form second phases. Zero field and in-field transport properties in Ag-cktd BaOz added Bi-2212 tapes had been improved at 4.2 K (1)-(3). SEM micrographs, pole figures, and transport critical currents versus magnetic field orientation suggest that Ba02 has a strong influence on the microstructural properties. Magnetization studies revealed that Ba02 does not affect the pinning properties of optimally added Bi-2212. To estimate the potential of Ba02 additions in creating possible pinning sites, TEM investigations were carried out focussing on sub-micrometer inclusions and growth defects in the superconducting phase.